Fix SpellCheck: add username to cspell dictionary

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: abhi3047office

specification/billingtrust/resource-manager/Microsoft.BillingTrust/BillingTrust/.cspell.yaml

@@ -10,3 +10,4 @@ words:
   - OAPI
   - scvmm
   - connectedvmware
+  - abmohanr